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  • Improve Log Exceptions

    - by Jaider
    I am planning to use log4net in a new web project. In my experience, I see how big the log table can get, also I notice that errors or exceptions are repeated. For instance, I just query a log table that have more than 132.000 records, and I using distinct and found that only 2.500 records are unique (~2%), the others (~98%) are just duplicates. so, I came up with this idea to improve logging. Having a couple of new columns: counter and updated_dt, that are updated every time try to insert same record. If want to track the user that cause the exception, need to create a user_log or log_user table, to map N-N relationship. Create this model may made the system slow and inefficient trying to compare all these long text... Here the trick, we should also has a hash column of binary of 16 or 32, that hash the message and the exception, and configure an index on it. We can use HASHBYTES to help us. I am not an expert in DB, but I think that will made the faster way to locate a similar record. And because hashing doesn't guarantee uniqueness, will help to locale those similar record much faster and later compare by message or exception directly to make sure that are unique. This is a theoretical/practical solution, but will it work or bring more complexity? what aspects I am leaving out or what other considerations need to have? the trigger will do the job of insert or update, but is the trigger the best way to do it?

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  • Creating an appropriate index for a frequently used query in SQL Server

    - by Slauma
    In my application I have two queries which will be quite frequently used. The Where clauses of these queries are the following: WHERE FieldA = @P1 AND (FieldB = @P2 OR FieldC = @P2) and WHERE FieldA = @P1 AND FieldB = @P2 P1 and P2 are parameters entered in the UI or coming from external datasources. FieldA is an int and highly on-unique, means: only two, three, four different values in a table with say 20000 rows FieldB is a varchar(20) and is "almost" unique, there will be only very few rows where FieldB might have the same value FieldC is a varchar(15) and also highly distinct, but not as much as FieldB FieldA and FieldB together are unique (but do not form my primary key, which is a simple auto-incrementing identity column with a clustered index) I'm wondering now what's the best way to define an index to speed up specifically these two queries. Shall I define one index with... FieldB (or better FieldC here?) FieldC (or better FieldB here?) FieldA ... or better two indices: FieldB FieldA and FieldC FieldA Or are there even other and better options? What's the best way and why? Thank you for suggestions in advance!

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  • N-gram split function for string similarity comparison

    - by Michael
    As part of excersise to better understand F# which I am currently learning , I wrote function to split given string into n-grams. 1) I would like to receive feedback about my function : can this be written simpler or in more efficient way? 2) My overall goal is to write function that returns string similarity (on 0.0 .. 1.0 scale) based on n-gram similarity; Does this approach works well for short strings comparisons , or can this method reliably be used to compare large strings (like articles for example). 3) I am aware of the fact that n-gram comparisons ignore context of two strings. What method would you suggest to accomplish my goal? //s:string - target string to split into n-grams //n:int - n-gram size to split string into let ngram_split (s:string, n:int) = let ngram_count = s.Length - (s.Length % n) let ngram_list = List.init ngram_count (fun i -> if( i + n >= s.Length ) then s.Substring(i,s.Length - i) + String.init ((i + n) - s.Length) (fun i -> "#") else s.Substring(i,n) ) let ngram_array_unique = ngram_list |> Seq.ofList |> Seq.distinct |> Array.ofSeq //produce tuples of ngrams (ngram string,how much occurrences in original string) Seq.init ngram_array_unique.Length (fun i -> (ngram_array_unique.[i], ngram_list |> List.filter(fun item -> item = ngram_array_unique.[i]) |> List.length) )

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  • C# algorithm for figuring out different possible combinations...

    - by ttomsen
    I have 10 boxes, each box can hold one item from a group/type of items, each 'group' type only fits in one of the 10 box types. The pool can have n number of items. The groups have completely distinct items. Each item has a price, i want an algorithm that will generate all the different possibilities, so i can figure out different price points. so a smaller picture of the problem BOX A - can have item 1,2,3,4 in it BOX B - can have item 6,7,8,9,10,11,12 BOX C - can have item 13,15,16,20,21 The items are stored in a db, they have a column which denotes which box they can go in. All box types are stored in an array, and I can put the items in a generic list. Anyone see a straightforward way to do this. I have tried doing 10 nested foreach's to see if i could find a simpler way. The nested loops will take MANY hours to run. the nested for each's basically pull all combinations, then calculate a rank for each combination, and store the top 10 ranked combination of items for output

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  • Help with SQL Server query

    - by Travis
    Sorry* this is what I should have put My query is creating duplicate entries for any record that has more than 1 instance (regardless of date) <asp:SqlDataSource ID="EastMonthlyHealthDS" runat="server" ConnectionString="<%$ ConnectionStrings:SNA_TRTTestConnectionString %>" SelectCommand="SELECT [SNA_Parent_Accounts].[Company], (SELECT [Monthly_HIP_Reports].[AccountHealth] from [Monthly_HIP_Reports] where ([Monthly_HIP_Reports].[YearMonth] = @ToDtRFC) AND ([SNA_Parent_Accounts].[CompID] = [Monthly_HIP_Reports].[CompID])) as [AccountHealth], [SNA_Parent_Accounts].[CompID] FROM [SNA_Parent_Accounts] LEFT OUTER JOIN [Monthly_HIP_Reports] ON [Monthly_HIP_Reports].[CompID] = [SNA_Parent_Accounts].[CompID] WHERE (([SNA_Parent_Accounts].[Classification] = 'Business') OR ([SNA_Parent_Accounts].[Classification] = 'Business Ihn')) AND ([SNA_Parent_Accounts].[Status] = 'active') AND ([SNA_Parent_Accounts].[Region] = 'east') ORDER BY [SNA_Parent_Accounts].[Company]"> <SelectParameters> <asp:ControlParameter ControlID="ddMonths" Name="ToDtRFC" PropertyName="Text" Type="String" /> </SelectParameters> </asp:SqlDataSource> Using SELECT DISTINCT appears to correct the problem, but I don't consider that a solution. There are no duplicate entries in the database. So it appears my query is superfically creating duplicates. The query should grab a list of companies that meet the criteria in the where clause, but also grab the Health status for each company in that particular [YearMonth] if present which is what the subquery is for. If an entry for that YearMonth is not present, then leave the Health status blank. but as stated earlier.. if you have an entry say for 2009-03 for CompID 2 and an entry for 2009-04 for CompID 2.. Doesn't matter what month you select it will list that company 2-3 times.

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  • How can I optimize the SELECT statement running on an Oracle database?

    - by Elvis Lou
    I have a SELECT statement in ORACLE: SELECT COUNT(DISTINCT ds1.endpoint_msisdn) multiple30, dss1.service, dss1.endpoint_provisioning_id, dss1.company_scope, Nvl(x.subscription_status, dss1.subscription_status) subscription_status FROM daily_summary ds1 join daily_summary ds2 ON ds1.endpoint_msisdn = ds2.endpoint_msisdn, daily_summary_static dss1, daily_summary_static dss2, (SELECT NULL subscription_status FROM dual UNION ALL SELECT -2 subscription_status FROM dual) x WHERE ds1.summary_ts >= To_date('10-04-2012', 'dd-mm-yyyy') - 30 AND ds1.summary_ts <= To_date('10-04-2012', 'dd-mm-yyyy') AND dss1.last_active >= To_date('10-04-2012', 'dd-mm-yyyy') - 30 AND dss1.last_active <= To_date('10-04-2012', 'dd-mm-yyyy') AND dss2.last_active >= To_date('10-04-2012', 'dd-mm-yyyy') - 30 AND dss2.last_active <= To_date('10-04-2012', 'dd-mm-yyyy') AND dss1.service <> dss2.service AND ( dss1.company_scope = 2 OR dss1.company_scope = 5 ) AND ( dss2.company_scope = 2 OR dss2.company_scope = 5 ) AND dss1.company_scope = dss2.company_scope AND ds1.endpoint_noc_id = dss1.endpoint_noc_id AND ds1.endpoint_host_id = dss1.endpoint_host_id AND ds1.endpoint_instance_id = dss1.endpoint_instance_id AND ds2.endpoint_noc_id = dss2.endpoint_noc_id AND ds2.endpoint_host_id = dss2.endpoint_host_id AND ds2.endpoint_instance_id = dss2.endpoint_instance_id AND dss1.endpoint_provisioning_id = dss2.endpoint_provisioning_id AND Least(1, ds1.total_actions) = 1 AND Least(1, ds2.total_actions) = 1 GROUP BY dss1.service, dss1.endpoint_provisioning_id, dss1.company_scope, Nvl(x.subscription_status, dss1.subscription_status); This query took about 26 minutes to return in my environment, but if I remove the section: dss1.last_active >= to_date('10-04-2012','dd-mm-yyyy') - 30 AND dss1.last_active <= to_date('10-04-2012','dd-mm-yyyy') AND dss2.last_active >= to_date('10-04-2012','dd-mm-yyyy') - 30 AND dss2.last_active <= to_date('10-04-2012','dd-mm-yyyy') AND it only took 20 seconds to run. We have index on the column last_active, I don't know why the section slow down the performance so much? any ideas?

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  • Are bad data issues that common?

    - by Water Cooler v2
    I've worked for clients that had a large number of distinct, small to mid-sized projects, each interacting with each other via properly defined interfaces to share data, but not reading and writing to the same database. Each had their own separate database, their own cache, their own file servers/system that they had dedicated access to, and so they never caused any problems. One of these clients is a mobile content vendor, so they're lucky in a way that they do not have to face the same problems that everyday business applications do. They can create all those separate compartments where their components happily live in isolation of the others. However, for many business applications, this is not possible. I've worked with a few clients, one of whose applications I am doing the production support for, where there are "bad data issues" on an hourly basis. Yeah, it's that crazy. Some data records from one of the instances (lower than production, of course) would have been run a couple of weeks ago, and caused some other user's data to get corrupted. And then, a data script will have to be written to fix this issue. And I've seen this happening so much with this client that I have to ask. I've seen this happening at a moderate rate with other clients, but this one just seems to be out of order. If you're working with business applications that share a large amount of data by reading and writing to/from the same database, are "bad data issues" that common in your environment?

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  • Retrieving models from form with ModelMultipleChoiceField

    - by colinjameswebb
    I am having difficulties with forms, specifically ModelMultipleChoiceField. I've pieced together this code from various examples, but it sadly doesn't work. I would like to be able to: Search for some Works on work_search.html Display the results of the search, with checkboxes next to each result Select the Works I want, via the checkboxes After pressing Add, display which works were selected. I believe everything is okay except the last part. The page simply displays "works" :( Here is the code - sorry about the length. Models.py class Work(models.Model): title = models.CharField(max_length=200) artist = models.CharField(max_length=200) writers = models.CharField(max_length=200) def __unicode__(self): return self.title + ' - ' + self.artist forms.py class WorkSelectForm(forms.Form): def __init__(self, queryset, *args, **kwargs): super(WorkSelectForm, self).__init__(*args, **kwargs) self.fields['works'] = forms.ModelMultipleChoiceField(queryset=queryset, widget=forms.CheckboxSelectMultiple()) views.py def work_search(request): query = request.GET.get('q', '') if query: qset = ( Q(title__icontains=query) | Q(artist__icontains=query) | Q(writers__icontains=query) ) results = Work.objects.filter(qset).distinct() form = WorkSelectForm(results) return render_to_response("work_search.html", {"form": form, "query": query }) else: results = [] return render_to_response("work_search.html", {"query": query }) def add_works(request): #if request.method == POST: form = WorkSelectForm(request.POST) #if form.isvalid(): items = form.fields['works'].queryset return render_to_response("add_works.html", {"items":items}) work_search.html {% extends "base.html" %} {% block content %} <h1>Search</h1> <form action="." method="GET"> <label for="q">Search: </label> <input type="text" name="q" value="{{ query|escape }}"> <input type="submit" value="Search"> </form> {% if query %} <h2>Results for "{{ query|escape }}":</h2> <form action="add_works" method="post"> <ul> {% if form %} {{ form.as_ul }} {% endif %} </ul> <input type="submit" value="Add"> </form> {% endif %} {% endblock %} add_works.html {% extends "base.html" %} {% block content %} {% if items %} {% for item in items %} {{ item }} {% endfor %} {% else %} <p>Nothing selected</p> {% endif %} {% endblock %}

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  • A question about entities, roles and interfaces in Entity Framework 4.

    - by mvole
    Hi, I am an experienced .NET developer but new to EF - so please bear with me. I will use an example of a college application to illustrate my problem. I have these user roles: Lecturer, Student, Administrator. In my code I envisage working with these entities as distinct classes so e.g. a Lecturer teaches a collection of Students. And work with 'is Student' 'TypeOf' etc. Each of these entities share lots of common properties/methods e.g. they can all log onto the system and do stuff related to their role. In EF designer I can create a base entity Person (or User...) and have Lecturer, Student and Administrator all inherit from that. The difficulty I have is that a Lecturer can be an Administrator - and in fact on occasion a Student can be a Lecturer. If I were to add other entities such as Employee and Warden then this gets even more of an issue. I could presumably work with Interfaces so a person could implement ILecturer and IStudent, however I do not see how this fits within EF. I would like to work within the EF designer if possible and I'm working model-first (coding in C#). So any help and advice/samples would be very welcome and much appreciated. Thanks

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  • Partial class or "chained inheritance"

    - by Charlie boy
    Hi From my understanding partial classes are a bit frowned upon by professional developers, but I've come over a bit of an issue; I have made an implementation of the RichTextBox control that uses user32.dll calls for faster editing of large texts. That results in quite a bit of code. Then I added spellchecking capabilities to the control, this was made in another class inheriting RichTextBox control as well. That also makes up a bit of code. These two functionalities are quite separate but I would like them to be merged so that I can drop one control on my form that has both fast editing capabilities and spellchecking built in. I feel that simply adding the code form one class to the other would result in a too large code file, especially since there are two very distinct areas of functionality, so I seem to need another approach. Now to my question; To merge these two classes should I make the spellchecking RichTextBox inherit from the fast edit one, that in turn inherits RichTextBox? Or should I make the two classes partials of a single class and thus making them more “equal” so to speak? This is more of a question of OO principles and exercise on my part than me trying to reinvent the wheel, I know there are plenty of good text editing controls out there. But this is just a hobby for me and I just want to know how this kind of solution would be managed by a professional. Thanks!

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  • how can modify or add new item into generic list of string's

    - by Sadegh
    hi, i want to remove some pretty words in list of words. public System.String CleanNoiseWord(System.String word) { string key = word; if (word.Length <= 2) key = System.String.Empty; else key = word; //other validation here return key; } public IList<System.String> Clean(IList<System.String> words) { var oldWords = words; IList<System.String> newWords = new string[oldWords.Count()]; string key; var i = 0; foreach (System.String word in oldWords) { key = this.CleanNoiseWord(word); if (!string.IsNullOrEmpty(key)) { newWords.RemoveAt(i); newWords.Insert(i++, key); } } return newWords.Distinct().ToList(); } but i can't add, remove or insert any thing in list! and exception NotSupportedException occured Collection was of a fixed size. how i can modify or add new item into generic list of string's?

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  • Output problem in mysql query in MFC program

    - by D.Gaughan
    Im currently working on a small MFC program that outputs data from a mysql database. I can get output when im using an sql statement that does not contain any variable eg. select album from Artists; but when i try to use a variable the program compiles but i get no output eg. mysql_perform_query(conn,select album from Artists where artists = '"+m_search_edit"'") Here is the function for mysql_perform_query: MYSQL_RES* mysql_perform_query(MYSQL *conn, const char* query) { // send the query to the database if (mysql_query(conn, query)) { // printf("MySQL query error : %s\n", mysql_error(conn)); // exit(1); } return mysql_use_result(conn); } And here is the code block for outputting the data: struct connection_details mysqlD; mysqlD.server = "www.freesqldatabase.com"; // where the mysql database is mysqlD.user = "**********"; // the root user of mysql mysqlD.password = "***********"; // the password of the root user in mysql mysqlD.database = "***************"; // the databse to pick // connect to the mysql database conn = mysql_connection_setup(mysqlD); CStringA query; query.Format("select album from Artists where artist = '%s'", CT2CA(m_search_edit)); res = mysql_perform_query(conn, query); //res = mysql_perform_query (conn, "select distinct artist from Artists"); while((row = mysql_fetch_row(res)) != NULL){ CString str; UpdateData(); str = ("%s\n", row[0]); UpdateData(FALSE); m_list_control.AddString(str); } The m_search_edit variable is the variable for an edit box. I am using Visual Studio 2008 with one copy of this program unicode and one nonunicode, I also have a version built with VC++ 6. Any tips on how I can get output from the databse using the m_search_edit variable??

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  • Performance of a get unique elements/group by operation on an IEnumerable<T>.

    - by tolism7
    I was wondering how could I improve the performance of the following code: public class MyObject { public int Year { get; set; } } //In my case I have 30000 IEnumerable<MyObject> data = MethodThatReturnsManyMyObjects(); var groupedByYear = data.GroupBy(x => x.Year); //Here is the where it takes around 5 seconds foreach (var group in groupedByYear) //do something here. The idea is to get a set of objects with unique year values. In my scenario there are only 6 years included in the 30000 items in the list so the foreach loop will be executed 6 times only. So we have many items needing to be grouped in a few groups. Using the .Distinct() with an explicit IEqualityComparer would be an alternative but somehow I feel that it wont make any difference. I can understand if 30000 items is too much and that i should be happy with the 5 seconds I get, but I was wondering if the above can be imporved performance wise. Thanks.

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  • How can I use a meter-style progress bar?

    - by Yadyn
    In Vista/7, the Windows Explorer shell window makes use of a special kind of static progress bar to display hard drive space. With default styles, this bar is blue colored and non-animated. It also turns red colored when it gets close to being full (low disk space). Using messaging, I can tell the Windows Forms ProgressBar control to update its state to Paused and Error (yellow and red colored, respectively), which works fine, but these are still specific to progress. In the Windows User Experience Guidelines, it specifically points out this "meter" variant of the Progress Bar: This pattern isn't a progress bar, but it is implemented using the progress bar control. Meters have a distinct look to differentiate them from true progress bars. They say it "is implemented using the progress bar control", so... how? What message could I send to the control to have it behave this way? I've seen that you can send messages for setting the bar color, but the documentation says these calls are ignored when visual styles are enabled. Nothing else in the Windows API documentation for raw ProgressBar controls seemed to suggest a way to do this. Am I just stuck making a custom drawn bar? I'd really like to utilize the OS whenever possible so that the application will appear consistent throughout different OS versions. I realize that pre-Vista versions probably won't support this, though. I'm looking for a Windows Forms solution, but I wonder if it is even exposed at all via Win32 API.

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  • remove duplicated array values in a function PHP

    - by Deividas Juškevicius
    I read all topics related to this question in stackoverflow and whole internet and cant find working sollution... Each owner has his item and when someone buy his item, owner gets an confirmation email, but when in cart is few same owner items, he gets several same email letters, so I need to remove dublicated array entries. I have tried to use DISTINCT and array_uniques functions but no luck. Any advices? I have an array and function to send mail.. function email($mail_array) { foreach(array_unique($mail_array) as $field => $value) { $result = mysql_query("select email from users where $field='$value'"); $row = mysql_fetch_array($result); $maail = mysql_real_escape_string($row['email']); $email_to = "".$maail.""; // rest of mail formatting code // create email headers $headers = 'From: '.$email_from."\r\n" . 'Reply-To: '.$email_from."\r\n" . 'X-Mailer: PHP/' . phpversion(); @mail($email_to, $email_subject, $email_message, $headers); } for ($i = 0; $i < $max; $i++) { $pid = $_SESSION['cart'][$i]['productid']; $owner = get_owner($pid); $mail_array = array( 'name' => $owner ); email($mail_array) //call function to send mail }

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  • How to handle xpath in SQL query while programming in Java

    - by Pratik
    I am trying to execute the SQL statement from my java application Due website restriction on url I have replaced http=htp for this post. SELECT DISTINCT(DID) FROM (SELECT e_id DID, xml_doc xml, rownum rn from employee_master_indexes)," + " table(XMLSequence(extract(xml,'//cf:SalesReport/ext:Sales/*//j:PersonAssignedIDDetails/j:PersonID/j:ID',"+ "'xmlns:j=\" htp://www.it.jvp.com/xmm/3.0.3\" xmlns:xsi=\" htp://www.w3.org/2001/XMLSchema\" " + "xmlns:ext=\" htp://xml.crossflo.com/xdm/3.0.3/extension\" xmlns:cf=\" htp://xml.crossflo.com/xdm/3.0.3\" ')))EMPID" + "WHERE extractValue(value(EMPID),'/j:ID', 'xmlns:j=\" htp://www.it.jvp.com/xmm/3.0.3\"') LIKE '%-%-%' AND rn BETWEEN 999 AND 2001"; but end up with 10/05/24 11:11:51 java.sql.SQLException: ORA-00933: SQL command not properly ended 10/05/24 11:11:51 at oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:138) 10/05/24 11:11:51 at oracle.jdbc.driver.T4CTTIoer.processError(T4CTTIoer.java:316) 10/05/24 11:11:51 at oracle.jdbc.driver.T4CTTIoer.processError(T4CTTIoer.java:282) 10/05/24 11:11:51 at oracle.jdbc.driver.T4C8Oall.receive(T4C8Oall.java:639) 10/05/24 11:11:51 at oracle.jdbc.driver.T4CStatement.doOall8(T4CStatement.java:113) 10/05/24 11:11:51 at oracle.jdbc.driver.T4CStatement.execute_for_describe(T4CStatement.java:431) 10/05/24 11:11:51 at oracle.jdbc.driver.OracleStatement.execute_maybe_describe(OracleStatement.java:1029) 10/05/24 11:11:51 at oracle.jdbc.driver.T4CStatement.execute_maybe_describe(T4CStatement.java:463) 10/05/24 11:11:51 at oracle.jdbc.driver.OracleStatement.doExecuteWithTimeout(OracleStatement.java:1126) 10/05/24 11:11:51 at oracle.jdbc.driver.OracleStatement.executeQuery(OracleStatement.java:1274) 10/05/24 11:11:51 at oracle_jdbc_driver_T4CStatement_Proxy.executeQuery() I am able to run this query properly on my sql prompt.Any guidance on what makes oracle give me this exception would be appreciated.

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  • Setting synthesized arrays causing memory leaks using nested arrays

    - by webtoad
    Hello: Why is the following code causing a memory leak in an iPhone App? All of the initted objects below leak, including the arrays, the strings and the numbers. So, I'm thinking it has something to do with the the synthesized array property not releasing the object when I set the property again on the second and subsequent time this piece of code is called. Here is the code: "controller" (below) is my custom view controller class, which I have a reference to, and I am setting with this code snippet: sqlite3_stmt *statement; NSMutableArray *foo_IDs = [[NSMutableArray alloc] init]; NSMutableArray *foo_Names = [[NSMutableArray alloc] init]; NSMutableArray *foo_IDsBySection = [[NSMutableArray alloc] init]; NSMutableArray *foo_NamesBySection = [[NSMutableArray alloc] init]; // Get data: NSString *sql = @"select distinct p.foo_ID, p.foo_Name from foo as p "; if (sqlite3_prepare_v2(...) == SQLITE_OK) { while (sqlite3_step(statement) == SQLITE_ROW) { int p_id; NSString *foo_Name; p_id = sqlite3_column_int(statement, 0); char *str2 = (char *)sqlite3_column_text(statement, 1); foo_Name = [NSString stringWithCString:str2]; [foo_IDs addObject:[NSNumber numberWithInt:p_id]]; [foo_Names addObject:foo_Name]; } sqlite3_finalize(statement); } // Pass the array itself into another array: // (normally there is more than one array in each array) [foo_IDsBySection addObject: foo_IDs]; [foo_NamesBySection addObject: foo_Names]; [foo_IDs release]; [foo_Names release]; // Set some synthesized properties (of type NSArray, nonatomic, // retain) in controller: controller.foo_IDsBySection = foo_IDsBySection; controller.foo_NamesBySection = foo_NamesBySection; [foo_IDsBySection release]; [foo_NamesBySection release]; Thanks for any help!

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  • How to exclude rows where matching join is in an SQL tree

    - by Greg K
    Sorry for the poor title, I couldn't think how to concisely describe this problem. I have a set of items that should have a 1-to-1 relationship with an attribute. I have a query to return those rows where the data is wrong and this relationship has been broken (1-to-many). I'm gathering these rows to fix them and restore this 1-to-1 relationship. This is a theoretical simplification of my actual problem but I'll post example table schema here as it was requested. item table: +------------+------------+-----------+ | item_id | name | attr_id | +------------+------------+-----------+ | 1 | BMW 320d | 20 | | 1 | BMW 320d | 21 | | 2 | BMW 335i | 23 | | 2 | BMW 335i | 34 | +------------+------------+-----------+ attribute table: +---------+-----------------+------------+ | attr_id | value | parent_id | +---------+-----------------+------------+ | 20 | SE | 21 | | 21 | M Sport | 0 | | 23 | AC | 24 | | 24 | Climate control | 0 | .... | 34 | Leather seats | 0 | +---------+-----------------+------------+ A simple query to return items with more than one attribute. SELECT item_id, COUNT(DISTINCT(attr_id)) AS attributes FROM item GROUP BY item_id HAVING attributes > 1 This gets me a result set like so: +-----------+------------+ | item_id | attributes | +-----------+------------+ | 1 | 2 | | 2 | 2 | | 3 | 2 | -- etc. -- However, there's an exception. The attribute table can hold a tree structure, via parent links in the table. For certain rows, parent_id can hold the ID of another attribute. There's only one level to this tree. Example: +---------+-----------------+------------+ | attr_id | value | parent_id | +---------+-----------------+------------+ | 20 | SE | 21 | | 21 | M Sport | 0 | .... I do not want to retrieve items in my original query where, for a pair of associated attributes, they related like attributes 20 & 21. I do want to retrieve items where: the attributes have no parent for two or more attributes they are not related (e.g. attributes 23 & 34) Example result desired, just the item ID: +------------+ | item_id | +------------+ | 2 | +------------+ How can I join against attributes from items and exclude these rows? Do I use a temporary table or can I achieve this from a single query? Thanks.

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  • Elegant Disjunctive Normal Form in Django

    - by Mike
    Let's say I've defined this model: class Identifier(models.Model): user = models.ForeignKey(User) key = models.CharField(max_length=64) value = models.CharField(max_length=255) Each user will have multiple identifiers, each with a key and a value. I am 100% sure I want to keep the design like this, there are external reasons why I'm doing it that I won't go through here, so I'm not interested in changing this. I'd like to develop a function of this sort: def get_users_by_identifiers(**kwargs): # something goes here return users The function will return all users that have one of the key=value pairs specified in **kwargs. Here's an example usage: get_users_by_identifiers(a=1, b=2) This should return all users for whom a=1 or b=2. I've noticed that the way I've set this up, this amounts to a disjunctive normal form...the SQL query would be something like: SELECT DISTINCT(user_id) FROM app_identifier WHERE (key = "a" AND value = "1") OR (key = "b" AND value = "2") ... I feel like there's got to be some elegant way to take the **kwargs input and do a Django filter on it, in just 1-2 lines, to produce this result. I'm new to Django though, so I'm just not sure how to do it. Here's my function now, and I'm completely sure it's not the best way to do it :) def get_users_by_identifiers(**identifiers): users = [] for key, value in identifiers.items(): for identifier in Identifier.objects.filter(key=key, value=value): if not identifier.user in users: users.append(identifier.user) return users Any ideas? :) Thanks!

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  • How to handle duplicate values in d3.js

    - by Mario
    First I'm a d3.js noob :) How you can see from the title I've got a problem with duplicated data and aggregate the values is no option, because the name represent different bus stops. In this example maybe the stops are on the fron side and the back side of a building. And of course I like to show the names on the x-axis. If i created an example and the result is a bloody mess, see jsFiddel. x = index name = bus stop name n = value I've got a json e.g.: [{ "x": 0, "name": "Corniche St / Abu Dhabi Police GHQ", "n": 113 }, { "x": 1, "name": "Corniche St / Nation Towers", "n": 116 }, { "x": 2, "name": "Zayed 1st St / Al Khalidiya Public Garden", "n": 146 }, ... { "x": 49, "name": "Hamdan St / Tariq Bin Zeyad Mosque", "n": 55 }] The problem: It is possible that the name could appear more then once e.g. { "x": 1, "name": "Corniche St / Nation Towers", "n": 116 } and { "x": 4, "name": "Corniche St / Nation Towers", "n": 105 } I like to know is there a way to tell d3.js not to use distinct names and instead just show all names in sequence with their values. Any ideas or suggestions are very welcome :) If you need more information let me know. Thanks in advanced Mario

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  • How should I manage/declare dependencies between open source C# projects?

    - by munificent
    I've got a game (a roguelike to be specific) in C# that I'm in the process of cleaning up to open source. One step I'd like to take is splitting it into three distinct pieces: A simple package of utility classes, things like 2D arrays, vectors, etc. A terminal UI package that gives you a curses-like display. It depends on 1. The actual game, which uses 1 and 2. Right now, these are all separate projects in the same solution, but I'd kind of like to make them completely separate projects (in the "open source project" sense, not the "visual studio project" use of the term) with their own names and repos. I think, at the very least, #1 is generally useful even if you aren't building game, and I don't want someone to have to build an entire game just to get some handy functions. What I'm not sure about is how to handle the dependencies if I split up the solution. If someone decides they want to sync the game, how should I ensure they also get 1 and 2? Include the built dependent .dlls in the games repo? Just document, "you need these other projects and they must be in a path relative to the game like this". Just leave it all one giant solution and a single repo. Something I'm not thinking of?

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  • managing classes when everything is relative to a user in nhibernate (orm)

    - by Schotime
    Firstly I have three entities. Users, Roles, Items A user can have multiple Roles. An item gets assigned to one or more roles. Therefore a user will have access to a distinct set of items. Now there is a few ways I can see this working. There is a Collection on Users which has Roles via a many-to-many assoc. Then each Role in this collection will have its own collection of Items. So for each user I would have to get the User (using nhib and fetch the roles and items with it) then either do a selectMany on the Items in each Role to get all the Items for the user or do a couple of foreach's to port the data to a view or dto model. Create a db trigger to automatically insert into another table that just has the relationship between user and items so that on my User entity I only have a Items collections which has all the items assigned to me. Some other way that i can't think of yet, because I'm new to nHibernate. Now i know that the trigger doesn't feel right but I'm not sure how to do this. We also have some hierarchy later where a user may be in charge of a group of users. If anyone could shed some light on how they go about these scenarios in nhibernate or another orm that would be great, or point be in a direction. I know that in the past you would have to enter all combinations into a table so that the query worked, but when you know sql its not too bad. If you need any other info then let me know. Cheers

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  • T-SQL Query, combine columns from multiple rows into single column

    - by Shayne
    I have seeen some examples of what I am trying to do using COALESCE and FOR XML (seems like the better solution). I just can't quite get the syntax right. Here is what I have (I will shorten the fields to only the key ones): Table Fields ------ ------------------------------- Requisition ID, Number IssuedPO ID, Number Job ID, Number Job_Activity ID, JobID (fkey) RequisitionItems ID, RequisitionID(fkey), IssuedPOID(fkey), Job_ActivityID (fkey) I need a query that will list ONE Requisition per line with its associated Jobs and IssuedPOs. (The requisition number start with "R-" and the Job Number start with "J-"). Example: R-123 | "PO1; PO2; PO3" | "J-12345; J-6780" Sure thing Adam! Here is a query that returns multiple rows. I have to use outer joins, since not all Requisitions have RequisitionItems that are assigned to Jobs and/or IssuedPOs (in that case their fkey IDs would just be null of course). SELECT DISTINCT Requisition.Number, IssuedPO.Number, Job.Number FROM Requisition INNER JOIN RequisitionItem on RequisitionItem.RequisitionID = Requisition.ID LEFT OUTER JOIN Job_Activity on RequisitionItem.JobActivityID = Job_Activity.ID LEFT OUTER JOIN Job on Job_Activity.JobID = Job.ID LEFT OUTER JOIN IssuedPO on RequisitionItem.IssuedPOID = IssuedPO.ID

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  • If attacker has original data, and encrypted data, can they determine the passphrase?

    - by Brad Cupit
    If an attacker has several distinct items (for example: e-mail addresses) and knows the encrypted value of each item, can the attacker more easily determine the secret passphrase used to encrypt those items? Meaning, can they determine the passphrase without resorting to brute force? This question may sound strange, so let me provide a use-case: User signs up to a site with their e-mail address Server sends that e-mail address a confirmation URL (for example: https://my.app.com/confirmEmailAddress/bill%40yahoo.com) Attacker can guess the confirmation URL and therefore can sign up with someone else's e-mail address, and 'confirm' it without ever having to sign in to that person's e-mail account and see the confirmation URL. This is a problem. Instead of sending the e-mail address plain text in the URL, we'll send it encrypted by a secret passphrase. (I know the attacker could still intercept the e-mail sent by the server, since e-mail are plain text, but bear with me here.) If an attacker then signs up with multiple free e-mail accounts and sees multiple URLs, each with the corresponding encrypted e-mail address, could the attacker more easily determine the passphrase used for encryption? Alternative Solution I could instead send a random number or one-way hash of their e-mail address (plus random salt). This eliminates storing the secret passphrase, but it means I need to store that random number/hash in the database. The original approach above does not require this extra table. I'm leaning towards the the one-way hash + extra table solution, but I still would like to know the answer: does having multiple unencrypted e-mail addresses and their encrypted counterparts make it easier to determine the passphrase used?

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  • Retrieving a unique result set with Core Data

    - by randombits
    I have a core data based app that manages a bunch of entities. I'm looking to be able to do the following. I have an entity "SomeEntity" with the attributes: name, type, rank, foo1, foo2. Now, SomeEntity has several rows if when we're speaking strictly in SQL terms. What I'm trying to accomplish is to retrieve only available types, even though each instance can have duplicate types. I also need them returned in order according to rank. So in SQL, what I'm looking for is the following: SELECT DISTINCT(type) ORDER BY rank ASC Here is the code I have so far that's breaking: NSError *error = NULL; NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init]; [fetchRequest setReturnsDistinctResults:YES]; [fetchRequest setPropertiesToFetch:[NSArray arrayWithObjects:@"type", @"rank", nil]]; NSEntityDescription *entity = [NSEntityDescription entityForName:@"SomeEntity" inManagedObjectContext:managedObjectContext]; [fetchRequest setEntity:entity]; // sort by rank NSSortDescriptor *rankDescriptor = [[NSSortDescriptor alloc] initWithKey:@"rank" ascending:YES]; NSArray *sortDescriptors = [[NSArray alloc] initWithObjects:rankDescriptor,nil]; [fetchRequest setSortDescriptors:sortDescriptors]; [sortDescriptors release]; [rankDescriptor release]; NSArray *fetchResults = [managedObjectContext executeFetchRequest:fetchRequest error:&error]; [fetchRequest release]; return fetchResults; Right now that is crashing with the following: Invalid keypath section passed to setPropertiesToFetch:

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